A novel which tackles fraught questions of identity, dislocation and loneliness through the life of an Ethiopian emigre in the US won this year's £10,000 Guardian first book award last night.

Dinaw Mengestu's Children of the Revolution tells the story of Sepha Stephanos, who flees to America to escape the violence of Ethiopia's communist revolution after witnessing his father's death at the hands of junta soldiers. Seventeen years later, running a struggling convenience store in a once grand but now dilapidated neighbourhood of Washington DC, Stephanos continues to wrestle with the difficulty of identifying his place in the new world.

The Guardian first book award is unique among literary prizes in that it is open to all debut writers regardless of genre. Children of the Revolution was joined on this year's shortlist by two other novels (Tahmima Anam's A Golden Age and Catherine O'Flynn's What Was Lost), Rosemary Hill's biography of the architect Augustus Pugin and Rajiv Chandrasekaran's excoriation of life in the fortified Green Zone in post-occupation Iraq, Imperial Life in the Emerald City.

Reviewers of Children of the Revolution were quick to point out the parallels between Stephanos's life and Mengestu's own. Born in Addis Ababa in 1978, Mengestu was just two years old when he and his mother and sister followed his father, who had been forced out by the revolution two years earlier, to the US. From there, however, their lives diverge: where Stephanos is trapped by his immigrant status, Mengestu attended Georgetown University and graduated from Columbia University's MFA programme. His clean, spare sentences and ability to deal with tragedy in a controlled and meticulous way won the judges' unanimous praise.

Speaking after the award, which was presented at a ceremony in Bloomsbury, the Guardian's literary editor and chair of the judging panel, Claire Armitstead, said that while each of the shortlisted books had their champions, the economy and power with which Mengestu depicted the dead-end lives of his characters saw him emerge as the winner. "Unusually for a first novel, there is no slack in his writing, no authorial vanity to interfere with his evocation of immigrant life in 21st-century America," she said.

In addition to the Waterstone's reading groups, represented on the panel by Stuart Broom, Armitstead was joined in the judging by the presenter Mariella Frostrup, journalist and author Simon Jenkins, Phillippe Sands QC, the Guardian's features editor, Katharine Viner, and the novelists Maggie O'Farrell and Kamila Shamsie. As well as applauding the novel's "beautiful writing", Shamsie praised the "many different layers of loss in the book, from the brutal to the barely-glimmering". It is, she said, "a book of quiet and haunting power, impossible to shake off long after you've turned the last page".

Mengestu, who is currently living in Paris and writing a second novel set in a small town in the American mid-West, accepted the award, which in previous years has gone to Zadie Smith and Jonathan Safran Foer among others, with visible delight. "It's amazing," he said afterwards. "I'm still stunned".

Full coverage of the awards, including audio interview with the winner, reviews and extracts guardian.co.uk/books

Children of the Revolution: an extract

On a good day I have 40 or maybe 50 customers. Most of them are stay-at-home moms or dads who've moved into one of the newly refurbished houses surrounding Logan's Circle. They stop in during an afternoon stroll with their children dangling around their necks like amulets to ward off age, sickness, unemployment, rain, death. They buy bottled water, toothpaste, cleaning supplies, and, if their kids are old enough, one of the small five-cent pieces of candy I've learned to keep next to the register for just this purpose. On those good days, which come once or twice a week, I make just over $400. I walk home at the end of the night feeling better, not only about my store but about this country. I think to myself, America is beautiful after all. There is more here. Gas is cheap. This is not a bad place. Things could be worse. And what else could I have done?